1. Technical Field
The inventive concept relates to a method of manufacturing a semiconductor device, and more particularly, to a method of manufacturing a semiconductor device using self-assembling polymer.
2. Related Art
A semiconductor industry requires desires to fabricate an integrated circuit (IC) having a higher integration density to obtain excellent performance and reduce a fabrication cost. With an increase in the degree of integration, a two-dimensional area occupied by each unit cell is reduced.
In response to reduction in an area of the unit cell, a design rule of several to several tens of nanometer which has a critical dimension of a nano scale is applied. Thus new technology for forming a fine pattern such as a fine contact hole pattern having an opening size of a nano scale and a fine line pattern having a nano-scale width, has been required.
A size of a structure such as a gate in a field effect transistor can be reduced by photolithographic technology.
The photolithographic process uses a principle in which a specific chemical material (photoresist) is chemically reacted by exposure to light to change its property. That is, the photolithographic process is a process of forming a pattern by selectively radiating light into the photoresist using a mask of a desired pattern.
The photolithographic process includes a coating process of coating a photoresist corresponding to a film of a photograph, an exposure process of selectively radiating light into the photoresist using a mask, and a development process of forming a pattern by removing or leaving a portion of the photoresist in which the light is radiated using a developer. The photoresist may be a positive photoresist or a negative photoresist. The photoresist may be a silicon (Si)-containing dry-developed resist. In the case of a positive PR, a photochemical reaction occurs in the photoresist exposed to light.
A pattern size obtained by a photolithographic process depends on a wavelength of light employed for an exposure process. Recent photolithographic processes use a short-wavelength light source such as KrF and ArF. Since the resolution of a pattern obtained from the short-wavelength light source is restricted around 0.1 μm, there is a limit to fabricate a high integration semiconductor device having a fine pattern of below the resolution. For example, performance degrades by aberration, focus, and an approximate effect when the light source is used.
In particular, a photoresist reflow process is performed to reduce a size of the contact hole pattern. However, the photoresist reflow process allows non-uniform photoresist at upper and at central portions of the photoresist. Thus, when a contact hole is formed using this method, the hole diameter at the upper portion of the photoresist becomes greater than that of the lower portion thereof, making difficult to obtain a desired hole pattern size.
A Resist Enhancement Lithography Assisted by Chemical Shrink (RELACS) process is also used as a method for forming a fine pattern. However, material used in this method is expensive. Also, a water-soluble polymer used in the RELACS process is not completely removed, but left on the pattern as a development residue to affect a subsequent etching process. Therefore, the RELACS process may degrade yield of a process and reliability of the semiconductor device.
As described above, it is difficult to increase integration of the semiconductor device due to technological limitation inherent to development of exposure equipment. The photoresist reflow process or the RELACS process in the related art can reduce a contact hole pattern size, but it is hard to control the pattern size or may generate other technical issues. In addition, it is desirable to form patterns uniformly in order to reduce approximate effect and improve a production yield.